This invention relates to methods for bonding silicone rubber materials directly to polyurethane materials without the use of adhesives and to articles manufactured by such methods. Polyurethane molecules having terminal hydroxyl or isocyanate groups will bond with silicone rubber materials and specifically with silicone rubber materials having alkoxy or halogen moieties associated with one or more of the silicon atoms in the rubber material. Polyurethane materials which have been stored for extended periods of time may be heat-treated prior to contacting the polyurethane with the silicone rubber material. Such heat treatment conditions the polyurethane to form a lasting and strong bond with the silicone material.
Treatment of various polymers by coating, for example, with silicone rubber materials is known. Such a treatment is described in my U.S. Pat. No. 4,851,009, the disclosure of which is incorporated by reference herein. Coating treatments such as those described in the aforementioned letters patent are useful and necessary in minimizing and even preventing the cracking which occurs in prostheses made of polymeric materials, such as polyurethane, following implantation in a living body and after extended in vivo use.
The treatment of urethane materials with silicone rubber materials also has applications in the manufacture of various articles which are not intended to be subjected to substantial or continuous in vivo use. Where such articles will not be implanted in a living body, it is not necessary to fully coat the article because cracking of the polymer is not an expected problem. However, it may be desirable to manufacture such articles out of a combination of materials such as polyurethane and silicone rubber materials in a manner whereby the silicone rubber is strongly bonded to the polyurethane to thereby eliminate the need for and the use of an adhesive in securing the component pieces of such objects together. The art has generally failed to provide such a method where previously manufactured polyurethane materials are to be bonded to silicone rubber materials and especially where the polyurethane material was originally prepared a substantial amount of time in advance of bonding to the silicone rubber material.
The present invention provides a method for manufacturing articles out of dissimilar materials such as polyurethanes and silicone rubber materials. Specifically, isocyanate- and/or hydroxy-terminated polyurethanes can be directly bonded to alkoxy- or halogen- terminated silicone rubber materials to bond the silicone material to the polyurethane and vice versa. Heating of the polyurethane will condition the surface of the polyurethane to render it more receptive to bonding with the rubber material. Time and temperature requirements for such heating generally depends on the particular urethane its glass transition temperatures and the amount of time which has lapsed since that urethane was originally processed (e.g. extruded).
The method of the present invention has applications in the manufacture of a variety of articles made from the types of materials described herein. For example, medical or surgical devices such as suture collars, vascular grafts, pacemaker lead insulators, heart valves, sutures and the like. Other applications such as silicone-coated polyurethane foam roof insulators, for example, are also contemplated.
It is accordingly an object of the present invention to provide a method for the manufacture of articles made from one or more polyurethanes and one or more silicone rubber materials.
It is another object of the present invention to provide a method for the manufacture of articles made from one or more polyurethane materials and one or more silicone rubber materials wherein the polyurethane material is heat treated to condition its surface for bonding to the silicone rubber material.
It is still another object of the present invention to provide articles manufactured according to the aforementioned method.
These and other objects and advantages of the present invention will be apparent to those skilled in the art upon consideration of the remainder of the disclosure.